package culton.android.data;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.content.Context;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
 
public class DatabaseHelper extends SQLiteOpenHelper {

	//The Android's default system path of your application database "/data/data/YOUR_PACKAGE/databases/";
    private static String DB_PATH = "/data/data/culton.android/databases/"; 
    private static String DB_NAME = "culton";
    
    private SQLiteDatabase myDataBase; 
	private Context myContext;
	
    /**
     * Constructor
     * Takes and keeps a reference of the passed context in order to access to the application assets and resources.
     * @param context
     */
    public DatabaseHelper(Context context) {
    	super(context, DB_NAME, null, 1);
        this.myContext = context;
    }	
 
    /**
     * Creates a empty database on the system and rewrites it with your own database.
     **/
    public void createDataBase() throws IOException{
    	boolean dbExist = checkDataBase();
 
    	if(!dbExist){
    		//do nothing - database already exist
    	} else {
 
    		//By calling this method an empty database will be created into the default system path
            //of your application so we are gonna be able to overwrite that database with our database.
        	this.getWritableDatabase();
 
        	try { 
    			copyDataBase();
    			Log.i("database", "Sucesso ao copiar banco de dados.");
    			
    		} catch (IOException e) {
    			Log.e("error", e.getMessage());
        		throw new Error("Error copying database");
        	}
    	}
    }
 
    /**
     * Check if the database already exist to avoid re-copying the file each time you open the application.
     * @return true if it exists, false if it doesn't
     */
    private boolean checkDataBase(){
    	SQLiteDatabase checkDB = null;
 
    	try{
    		String myPath = DB_PATH + DB_NAME;
    		checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
 
    	} catch(SQLiteException e) {
    		//database does't exist yet.
    	}
 
    	if(checkDB != null){
    		checkDB.close();
    	}
 
    	return checkDB != null ? true : false;
    }
 
    /**
     * Copies your database from your local assets-folder to the just created empty database in the
     * system folder, from where it can be accessed and handled.
     * This is done by transfering bytestream.
     * */
    private void copyDataBase() throws IOException{
 
    	//Open your local db as the input stream
    	InputStream myInput = myContext.getAssets().open(DB_NAME);
 
    	// Path to the just created empty db
    	String outFileName = DB_PATH + DB_NAME;
 
    	//Open the empty db as the output stream
    	OutputStream myOutput = new FileOutputStream(outFileName);
 
    	//transfer bytes from the inputfile to the outputfile
    	byte[] buffer = new byte[1024];
    	int length;
    	while ((length = myInput.read(buffer))>0) {
    		myOutput.write(buffer, 0, length);
    	}
 
    	//Close the streams
    	myOutput.flush();
    	myOutput.close();
    	myInput.close();
 
    }
 
    public void openDataBase() throws SQLException{
    	//Open the database
        String myPath = DB_PATH + DB_NAME;
    	myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
    }
 
    @Override
	public synchronized void close() {
    	if(myDataBase != null)
    		myDataBase.close();
    	super.close();
	}
 
	@Override
	public void onCreate(SQLiteDatabase db) {
	}
 
	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
 
	}
 
}
